Material Moisture Research Articles

Moistening of Walls Caused by Damage to Terraces - Research Studies and Numerical Simulations

The aim of the article is to determine the impact of terrace damage on the moisture of adjacent external walls. Changes in moisture of wall structures can be diagnosed based on different measurement methods. In the building being the subject of the research, the damage to the terrace was caused by the moisture of adjacent external walls, made of solid ceramic bricks. On the basis of macroscopic studies, the causes of irregularities were determined. Conducted measurements of water content of individual parts of the external wall made of solid ceramic bricks were made by non-invasive method and destructive method. Measurements of water content by non-destructive method were carried out using a measuring instrument with a probe to measure material moisture. The research showed differentiation of the water content of walls depending on the location in relation to the source of moisture. During the non-destructive tests carried out inside the building, the surface moisture of the solid ceramic brick, constituting the construction of external walls and lime plaster, was measured. Measurements of water content of plaster and brickwork, qualifying them as wet walls. In places outside the area of moisture, the water content of plaster and solid bricks were several times lower. The destructive tests were carried out using the drying-weight method. In order to obtain the results of water content in the area of moisture and outside the moisture area, 3 samples of solid bricks were collected. The average water content of the ceramic brick wall in the places of occurring moisture, they were three times higher than the water content of the brick outside the moisture area. The obtained test results indicate significant differences between the moisture of the brick examined in the near-surface area and water content inside the wall. On the basis of obtained results of laboratory tests, numerical calculations were carried out using WUFI 2D software. Numerical simulations made it possible to present changes in water content of a solid brick over a period of three years. Based on the carried out tests and numerical calculations, it can be concluded that despite relatively large differences in the initial water content of wall parts in moist and non-moist areas, after a period of 3 years, the moisture status for both analysed cases is similar and occurring water content differences are practically negligible.

Revisiting the thermal recrystallization of mechanically amorphized lignocellulose

The products of mechanical activation of lignocellulose are subject to the process of recrystallization of amorphized cellulose sections in some cases, this process reduces the efficiency of subsequent chemical and enzymatic treatment of plant raw materials. The process of recrystallization was studied on lignin-containing raw material - wheat straw. The crystal structure, particle and crystallite size of wheat straw ware studied by X-ray diffraction and granulometric analysis. It was found that the degree of crystallinity of cellulose in the composition of wheat straw decreases from 70 to 19 % in the process of mechanical activation in an AGO-2 planetary ball mill, the destruction of cellulose chains is observed predominantly along the [010] direction. The grinding limit was reached after 10 minutes of activation. Thermocycling at the boiling point of liquid nitrogen (-196 °C ) and at 180 °C of lignocellulose revealed that under these conditions the degree of recrystallization of amorphous regions of cellulose is negligible, which can be explained by the presence of lignin and a low water content in a material with a material moisture content (about 5.0 wt. %).

RESEARCH OF STRAW PYROLYSIS THERMAL EFFECTS FOR ESTIMATION OF POSSIBILITY ITS IMPLEMENTA-TION IN AUTOTHERMAL MODE

The aim of the work is research of straw pyrolysis in various modes, the determination of process thermal effects and estimation of straw thermal processing possibility in the autothermal mode.
 Physical experiment and differential thermal analysis were used as research methods. Thermotechnical characteristics of raw materials are determined by ISO 1171:2010, GOST R 55660-2013 and a bomb calorimeter; thermal and physical characteristic are determined by the analyzer of thermal diffusivity Discovery Laser Flash DLF-1200.
 In result of the work is established that thermal effects occur in the straw after heating to 200 °C. The first shows of exothermic reactions are observed when the reactor is heated to 303 °C – in this case the temperature of the straw reaches 308.8 °C. By differential thermal analysis is established that the temperature range of heat input was set from 235 to 575 °C and value of the thermal effect in this range was set 1475 kJ/kg. For this range, the heat costs for the organization of pyrolysis in the autothermal mode and the total thermal effect of the process are calculated. The calculation results showed that the maximum thermal effect (398.9 kJ/kg) can be obtained at a pyrolysis temperature of 460 °C. For these conditions, the influence of the initial straw moisture content on the autothermality of pyrolysis process was evaluated and it was established that process can be organized due to its own thermal effects when the raw material moisture is less than 30.5%.

Effect of Matrix and Graphite Filler on Thermal Conductivity of Industrially Feasible Injection Molded Thermoplastic Composites.

To understand how the thermal conductivity (TC) of virgin commercial polymers and their composites with low graphite filler amounts can be improved, the effect of material choice, annealing and moisture content is investigated, all with feasible industrial applicability in mind focusing on injection molding. Comparison of commercial HDPE, PP, PLA, ABS, PS, and PA6 based composites under conditions minimizing the effect of the skin-core layer (measurement at half the sample thickness) allows to deduce that at 20 m% of filler, both the (overall) in- and through-plane TC can be significantly improved. The most promising results are for HDPE and PA6 (through/in-plane TC near 0.7/4.3 W·m−1K−1 for HDPE and 0.47/4.3 W·m−1K−1 for PA6 or an increase of 50/825% and 45/1200% respectively, compared to the virgin polymer). Testing with annealed and nucleated PA6 and PLA samples shows that further increasing the crystallinity has a limited effect. A variation of the average molar mass and moisture content is also almost without impact. Intriguingly, the variation of the measuring depth allows to control the relative importance of the TC of the core and skin layer. An increased measurement depth, hence, a higher core-to-skin ratio measurement specifically indicates a clear increase in the through-plane TC (e.g., factor 2). Therefore, for basic shapes, the removal of the skin layer is recommendable to increase the TC.

Role of unsaturated soil above a heavily contaminated aquifer in the natural attenuation of arsenic

Large attenuation of arsenic is observed in a shallow aquifer in central Mexico, where the concentration decreases from 91.5 to 11.3 mg/L, over 1.3 km horizontal distance. To investigate possible mechanisms of attenuation of this pollutant, we dug a pit between the surface and the saturated zone. We then described the soil profile and determined arsenic and iron concentrations in soil samples as a function of depth. Next, we determined particle size distribution, bulk density, particle density, soil moisture and porosity of the soil material. We also analyzed arsenic concentration in the groundwater. The 2.2 m deep profile intersected 4 soil horizons (A, AB, B1 and B2). We found arsenic accumulation in the B2 horizon, directly overlying the saturated zone. These accumulations coincide with the thickness of the capillary fringe, revealing that arsenic is drawn up in the soil profile by capillary rise of arsenic-contaminated groundwater. Furthermore, arsenic accumulation showed a direct relationship with iron, likely due to arsenic adsorption on iron oxides. Results from this study contribute to understanding a capillary-driven natural attenuation mechanism that removes contaminants from groundwater by sinking them in the capillary fringe.

Determination of Thermal Conductivity Coefficient of Moist Sodium Carboxymethyl Cellulose

The heat exchange process of moist sodium carboxymethyl cellulose is studied. The method for determining the thermal conductivity coefficient of a moist disperse material is developed. The thermophysical properties of sodium carboxymethyl cellulose are determined. The influence of moisture content and density of the material on its thermal conductivity coefficient is studied. An empirical equation is derived by processing the experimental data to calculate the thermal conductivity coefficient of sodium carboxymethyl cellulose at different densities of the moist material.

Effects of Moisture Content and Additives on the Fermentation Quality and Degradation of Glycoalkaloids in Potato (<i>Solanum tuberosum</i>) Vine Silage in Tibet

The objectives of this research were to evaluate the effects of raw material moisture content and additives on the fermentation quality and degradation of glycoalkaloids in potato vine silage and to explore new approaches for feedstuff preservation with the aim of providing a source of sustainable livestock feed. Potato vine was partially wilted to three different target moisture contents [approx. 75% (M1), 65% (M2), and 55% (M3)] and treated with (1) formic acid [1.5% fresh weight (FW), FA]; (2) pre-fermented juices (5.0 mL kg−1 FW, PFJ); (3) corn flour (100 g kg−1 DM, CF); (4) potato pulp (30% FW, PP); and (5) no additives (control). After 45 days of ensiling with polyethylene (100 mL), the fermentation quality, chemical composition, and concentration of glycoalkaloids were determined. The results showed that silage quality and glycoalkaloid concentration were significantly influenced by moisture content and additives (P < 0.05). Lactic acid (LA), pH, acid detergent fiber (ADF), and neutral detergent fiber (NDF) increased slightly with decreasing moisture content; in contrast, the concentration of LA/AA declined. LA content was highest and pH and acetic acid (AA) were lowest at M1 compared with M2 and M3. Little to no butyric acid (BA) was detected in the presence of additives. The FA-treated silage exhibited a significantly reduced pH value and ammonia-N/total-N (NH3-N/TN) content (P < 0.05) and an increased concentration of LA and water-soluble carbohydrates (WSCs). PP-treated silage provided sufficient fermentation substrate, and the DM and WSC contents increased significantly (P < 0.05) compared with the PFJ and CF treatments. Supplementation with PFJ resulted in the pH of the ensiled forage stabilizing at approximately 4.40. With the addition of CF, the LA:AA ratios of the different moisture content treatments were 2.42, 2.15, and 1.75, respectively, which were significantly lower than 3:1 in the other treatments at all moisture contents. The potato glycoalkaloid content of the PV silage increased with decreasing moisture level. Glycoalkaloid concentration was significantly reduced to 0.55, 4.57, and 7.73 100 mg g−1, respectively (P < 0.05), in the different moisture treatments by the addition of FA. In conclusion, the best quality PV silage was produced at 75% moisture content with the addition of FA. Additive ensiling thus constitutes an effective approach for potato vine preservation.

Indirect measurements of water content using TDR-inferred dielectric permittivity and electrical resistivity

The measurement of moisture distribution in Engineered Barrier Systems (EBS) in salt mines and deep geological disposals is essential in order to monitor fluid ingress and record data for long-term security analyses. Additionally, soil moisture content has influence over the mechanical properties of the soil as well as plant growth, soil stability and contaminant transport to cite some. Therefore, finding affordable and reliable ways to determine moisture content, quickly and in the field without sampling, is of great interested among people in different subject areas. Time-domain reflectometry (TDR) has become a recognized electromagnetic method for non-destructive measurement of dielectric permittivity and electrical conductivity of moist porous materials. It turns out that both these measurements depend on the material moisture content, among other things. This paper presents a series of calibration tests performed on soil samples. TDR probes were used to obtain the dielectric permittivity and electrical conductivity of the samples. As a consequence, relationships between these measurements and the samples' volumetric water content were later established. These relationships can then be used to indirectly determine that important information of water content on similar soil material using cheap, quick and non-destructive TDR probes.

On the Technology of Sediment Sewage Utilization

The solution of the problem of disposing of human waste, including sewage sludge, is an important task of environmental technologies, which today use modern energy achievements, safe combustion, and energy utilization. The specific goal of the present work was the qualitative improvement of technologies of this kind, not so much for the sake of obtaining a large energy output but for the creation of an efficient, affordable, and ecologically perfect equipment based on advanced developments in the field of power generation on wet fuels. The possibility for successful implementation of new technologies is oriented towards the drying of moisture in organic materials and gasification of dried mass. The examples of new equipment are not yet experimentally tested.

A Noninvasive TDR Sensor to Measure the Moisture Content of Rigid Porous Materials.

The article presents the potential application of the time domain reflectometry (TDR) technique to measure moisture transport in unsaturated porous materials. The research of the capillary uptake phenomenon in a sample of autoclaved aerated concrete (AAC) was conducted using a TDR sensor with the modified construction for non-invasive testing. In the paper the basic principles of the TDR method as a technique applied in metrology, and its potential for measurement of moisture in porous materials, including soils and porous building materials are presented. The second part of the article presents the experiment of capillary rise process in the AAC sample. Application of the custom sensor required its individual calibration, thus a unique model of regression between the readouts of apparent permittivity of the tested material and its moisture was developed. During the experiment moisture content was monitored in the sample exposed to water influence. Monitoring was conducted using the modified TDR sensor. The process was additionally measured using the standard frequency domain (FD) capacitive sensor in order to compare the readouts with traditional techniques of moisture detection. The uncertainty for testing AAC moisture, was expressed as RMSE (0.013 cm3/cm3) and expanded uncertainty (0.01–0.02 cm3/cm3 depending on moisture) was established along with calibration of the applied sensor. The obtained values are comparable to, or even better than, the features of the traditional invasive sensors utilizing universal calibration models. Both, the TDR and capacitive (FD) sensor enabled monitoring of capillary uptake phenomenon progress. It was noticed that at the end of the experiment the TDR readouts were 4.4% underestimated and the FD readouts were overestimated for 12.6% comparing to the reference gravimetric evaluation.

Stochastic modelling of hygrothermal performance of highly insulated wood framed walls

As energy consumption has become an important issue in building design, most building codes require a higher insulation level for building envelopes to improve the building's energy efficiency. However, the highly insulated walls may lead to a higher risk of moisture problems. Although hygrothermal simulation has been widely used to investigate the moisture performance of wood framed walls, the uncertainties of input parameters such as material properties, boundary conditions and moisture loads, may lead to discrepancies between simulation results and actual performance of the envelope. This paper investigates the hygrothermal performance of highly insulated wood framed walls using a stochastic approach, which combines the Latin Hypercube Sampling method and Factorial Design to take into account the uncertainties of material properties, boundary conditions and moisture loads (air leakage and rain leakage). The investigated walls include an I-joist deep cavity wall, two exterior insulated walls, and a conventional 2 × 6 stud wall as the baseline. It is found that under the moisture loads introduced (i.e. air leakage and rain leakage), the exterior insulated walls have a lower mold growth risk than the deep cavity wall and the 2 × 6 stud baseline wall. The uncertainties of material properties do not result in significant variations in simulation results such as moisture content and mold growth index as uncertainties of moisture loads do. The hygrothermal performance of these highly insulated walls is more sensitive to moisture loads and the significance of the moisture loads (air leakage and rain leakage) depends on climatic conditions.

Particle Size Distribution and Physicochemical Properties of Pellets Made of Straw, Hay, and Their Blends

The aims of the study were (a) the determination of the physicochemical characteristics of properties of pellets made of shredded residue from hay, wheat straw, and their blend at a ratio of 50:50, and (b) the determination of a mathematical model of pellet durability, using a response surface method. Tests were conducted according to applicable standards. As a result of thermal changes during the pressure agglomeration process, the material moisture content of pellets had slightly decreased versus raw three biomasses by 0.50% w.b. (wet basis) to a final value within the range of 5.56–5.87% w.b. The pellet properties of the blend were not adequately represented by the arithmetic mean of their components. Pellets made of hay, straw, and their blend, had DM (DM—dry matter) specific densities of 1034, 974, and 1102 kg m−3, respectively. The densities showed correlation with calorific values (r = 0.637), which were in the range of 16.07–17.00 MJ kg−1. The pellet durability coefficient correlated negatively with particle size and biomass moisture content. On the basis of previous conclusions, a non-linear mathematical model was formulated to account for the pellet durability coefficient relative to pellet moisture, and the relation of particle sizes and specific density to pellet bulk density.

FIRE BEHAVIOR VARIABLES AND HAZARD INDICES OF FOREST FIRES

ABSTRACT The objective of this study was to evaluate the performance of different fire hazard indices (FWI, FMA, FMA+, Telicyn, Nesterov, P-EVAP and EVAP/P), taking into account the fire behavior variables and the susceptibility to fire expressed by the moisture of the combustible material. For this purpose, controlled burnings were performed at different times and information was recorded in relation to the meteorological conditions, characteristics of the combustible material and fire behavior variables. In general, all the indices presented significant correlations with both the moisture of the combustible material and the behavior of the fire. However, in general, a higher linear correlation of components of the Canadian Fire Weather Index (FWI) system was observed in predicting fire behavior and EVAP / P index in fuel moisture. The consistency of the correlations between the various indices and the analyzed variables makes the methodology possible to be used in any place, facilitating the decision making in regions where records of occurrences of forest fires are absent or unreliable.

Cost-Effective Testing Solutions for Sealing Material With IR Package

Hermeticity is one of the critical issues for infrared (IR) device package since the leakage will impair the functionality of the device. In this paper, two types of tests are conducted, i.e., moisture sensitivity test and helium leakage test. Pure material moisture sensitivity test is done in the first step, for the samples are made of pure hermetic sealing material and the cost is very low. The samples are subjected to moisture sensitivity level 1 (MSL1) condition, then desorbed by isothermal thermogravimetric analysis TGA at constant temperature 85 °C, and then followed by subsequent simulations to compare void penetration time and final relative humidity for different types of materials. The results show that the simulation can extend the time of the test to the fully dry/saturated condition, so that the test time/labor cost can be greatly reduced. The test results show that epoxy-based materials are suitable for this method. The moisture diffusion data repeatability is quite good and strictly follows Fick’s law. For glass material, TGA test has limitations in sample preparation. Voids are generated in glass samples during screen printing, which will lead to inaccurate test results. Then, helium leakage test is done by using alumina substrate bottom casing hermetically sealed by a silicon filter as the testing sample. The selected sealing materials are the ones with longer penetration time in TGA test and simulation. Bonding surfaces have no surface finish considering low cost. Sample preparation is not limited to epoxy-based materials. High-temperature storage (HTS) and thermal cycling (TC) are carried out to detect the hermeticity changes. The results show that some of the glass samples have peeling issues with anti-reflective coating after reliability test, although helium leak rate is slightly better. In conclusion, the advantage of moisture sensitivity test is low cost and can identify whether the material can pass or fail MSL1 condition. However, helium leakage test has fewer limitations in sample preparation. Combined with TC and HTS, helium leakage test can detect the material degradation and bonding quality effect. TGA and helium leakage test are combined together to enhance the hermeticity of IR package in this paper.

Determination of geometrical and viscoelastic properties of PLA/PHB samples made by additive manufacturing for urethral substitution

Additive manufacturing has a great potential for creating hard tissue substitutes, such as bone and cartilage, or soft tissues, such as vascular and skin grafts. This study is a pilot study for 3D printing of a new material mixture potentially used as a tubular substitute for urethra replacement. This new mixture is a blend of polylactic acid (PLA) and polyhydroxybutyrate (PHB).The basic aspect that affects the 3D printing process is correct material preparation and setting of 3D printer parameters.Selection of material and printing parameters depend on printing technology. The printing technology affects material behavior during printing process. The goal of preprocessing and 3D printing process is to provide stabile conditions during manufacturing to obtain usable printed samples.The study deals with preparation of material before 3D printing – material drying. Moisture in material affects material degradation and viscosity during printing. According to this, it is necessary to verify recommended drying parameters. Verification was performed by printing strand samples from dried and non-dried material and also by calculating and comparing respective viscosities that change in time. Printed strand clearly show that non-dried material degrades in less than 10 min, what leads to inappropriate application in short-time printing. Dried material shows significant stability and degrades slightly during selected time span. For metrological verification of material stability two sample types were designed and manufactured – a cubic sample which represents basic scaffold structures and a tubular one that serves as urethra substitution. Obtained results showed appropriate usability of selected technology and printing parameters for PLA / PHB material blend.

Evaluation of selected physical and mechanical properties of briquettes produced from cones of three coniferous tree species

The aim of the research was to determine the production viability and mechanical durability of briquettes made of shredded cones of three species: Scots pine, Norway spruce and European larch The agglomeration was carried out under constant operating conditions (at 20% of material moisture content, briquette diameter of 50 mm, at throughput of 50 kg h−1) in an industrial briquetting press. The particle size distribution of the shredded material was determined. The produced briquettes were evaluated for their density, mechanical durability and compressive strength. At moisture content of approximately 20%, the highest briquette density (1078 kg m−3), durability (97.87%) and compressive strength (9.69 MPa) were obtained for spruce briquettes. Pine cone briquettes showed the lowest density (938 kg m−3) and compressive strength (2.81 MPa), while larch cone briquettes had the lowest durability (87.58%). The produced briquettes were of high quality in terms of physical and mechanical characteristics. The novelty of research was the use of crushed cones of coniferous species, which are waste in seed extraction facilities, and due to the low bulk density, they are difficult to store and transport over long distances. After agglomeration, they form briquettes with good physical and mechanical parameters that can be used in local heating plants and stoves.

The Study of Microbiological Safety of Germinated Seeds of Broad Beans in the Process of their Production and Storage

Microbiological purity of the finished products based on bio-activated seed and grain requires special attention, as the level of moisture in bio-activated raw materials is 42-44%, which is a pleasant environment for the development of microorganisms. Therefore, the search for effective ways to increase the microbiological safety of sprouted raw materials and finished products on their basis is always actual. Germinated cereal products, likewise natural, are being used in health-improving diets. Research conducted last years in this direction for the inventions of the products of functional purpose have obtained huge scales. In the process of obtaining germinated products, both at the beginning of seed preparation and pre-soaking, it is possible to significantly reduce the microbiological contamination, due to the soft mode of preliminary short-term hydrothermal treatment which removes the most charged part of the beans, the seed’s shell. Along with this, accelerates the process of preparation of the propagated samples, increasing their yield and improving the nutritional value of the final product. Based on conducted studies, it was found that, it is recommended to expose the dry seeds to short-term hydrothermal (moisture- thermal) treatment, simultaneously removing the seed’s shell in order to improve the microbiological purity of bio-activated faba bean seeds. In addition, studies have shown that storing sprouted seeds of faba beans in an insoluble form at a temperature of + 6 0C in polyethylene bags up to four days ensures their safety. It was revealed that natural seeds in the process of preparation for germination have two times more sowing than the seeds freed from bran covering by preliminary moisture-heat treatment. A similar picture is also observed in the ready-sprouted samples, i.e. seeds sprouted in kind have about two times more sowing than seeds sprouted in a rusty form. It was found that in the samples of broad bean seeds, the decrease in the development of microflora in them occurs in several forms. Thus, preliminary short-term hydrothermal treatment of dry seeds in order to accelerate the process of bioactivation and scaling simultaneously reduces microbiological contamination. This is primarily achieved by the effect of high temperature effect on the seed coat, where the most undesirable microorganisms are collected. Proceeding from the foregoing, the issues of the change in the microbiological contamination of germinating seeds of broad beans in the process of receiving and storing them in a plastic bag in the cold (+ 6 0C) were studied too. Thus, the application of a directional regime for germination of broad bean seeds in an insoluble form makes it possible to obtain a seed mass (semi-finished product) from a less microbiological sowing which is stable for storage and use.

Process Efficiency and Energy Consumption During the Extrusion of Potato and Multigrain Formulations

Abstract The aim of the research was to determine the effect of extrusion conditions (various moisture content of raw materials and screw rotation speed), as well as the effect of recipe composition on the process efficiency and the energy consumption during treatment of potato and multigrain products. The efficiency of the extrusion process (Q) was determined by the mass of the product obtained at a given time for all prepared raw material mixtures and the process parameters used, while the specific mechanical energy demand was determined using the SME index. The obtained results allow to conclude that the level of raw materials moisture content had a greater impact on the efficiency and energy consumption of the extrusion process than the variable screw speed during the treatment. The efficiency of the process increased with the increasing moisture of the tested compositions, while a decrease in the requirements of SME was observed. The use of differentiated raw material compositions also influenced the Q and SME values determined during the tests.

Hygrothermal wave characteristic of nanobeam-type inhomogeneous materials with porosity under magnetic field

Flexural and longitudinal wave behaviors of nanobeams made of nanoporous-graded materials while surrounded by Winkler-Pasternak foundation, subjected to the longitudinal magnetic field and exposed to the hygrothermal environment are studied analytically. To this end, the governing equation derived by Euler–Bernoulli beam theory in conjunction with the nonlocal strain gradient theory is defined by employing Hamilton’s principle. By adopting an analytic model, the flexural and longitudinal dispersion relations between phase velocity and wave number are derived. The reliability of the present method is confirmed by comparing the obtained results with those stored in the literature. Finally, the effects of the power-law index, porosity volume fraction, nonlocal and material characteristic parameters, uniform temperature and moisture rise, elastic foundation parameters, magnetic field intensity, and wave number are also investigated in detail. It is found that the small-scale parameters are more influential in higher wave numbers where the wavelength is close to the length scale of nanostructures. However, foundation parameters, porosity volume fraction, and longitudinal magnetic field are more influential in lower wave numbers.

An experimental investigation on biogases production from Chinese herb residues based on dual circulating fluidized bed

In this paper, pyrolysis gasification experiment was carried out on a dual circulating fluidized bed gasifier using Chinese herb residues as raw material, and the effects of gasification temperature, the moisture content of raw materials, air equivalence ratio ER and steam to biomass mass ratio (S/B) on gasification characteristics were studied. The results show that the increase of gasification temperature can promote the gasification reaction and improve the gas production quality as well as the gasification efficiency. The rise of moisture content of raw materials leads to the decrease of the gasification temperature and φCO, the significant increase of φCO2, φH2, gas heat value and gasification efficiency all showed the tendency to increase first and then decrease. With the increase of ER, the combustible gas, especially φCO reduced continuously, leading to the gradual decrease of the calorific value of gas, φCO2, carbon conversion rate and gasification efficiency increased firstly and then decreased. A certain amount of steam ratio can improve the gas quality and the gasification efficiency, but excessive steam will restrain the gasification, S/B has a suitable threshold range. When the raw material moisture content was controlled between 5 and 10%, the gasification temperature was between 750 and 800 °C, ER 0.23–0.26 and S/B 0.4–0.6, the residue gasification system in dual circulating fluidized bed displays good gasification characteristics with more than 8 MJ/m3 the calorific value and 75% gasification efficiency. The results can provide a theoretical reference for the improvement of dual circulating fluidized bed gasification process and the further deepening utilization of Chinese herb residue resources.